Derek:
You are apparently describing a very unusual set of error codes for a car with the proper engine and transmission fitted. I say "apparently" because it really is hard to decipher what you mean.
The codes you describe would lead someone to think that maybe the wrong engine / transmission combination is in the car. AND, your title indicates you are looking at a V6 engine, which never came in a MY 97 XJR.
So, when we try and understand what might be happening, and your descriptions are very hard to read, and coupled with your "screw you" attitude, it makes it hard to know how to help you.
Please confirm that a V6 and not a straight 6 (I6) engine is in your car. If so, how did it get there? If not, when did this problem first appear? In other words, did the car come into your possession with the problem already there?

I assure you that many members of this forum will go out of their way to help someone, but if you take a deep breath and read the responses your post caused, I think you will recognize you need to conform a little to get the help.

 

Hey Derek, I'm no hot mechanic, so I don't know how to advise you re your problem, but without wanting to appear to be condescending perhaps you will accept this tidying up of your first post so that the knowledgeable guys can help.
"Hi guys, I recently bought an XJR6 as a good deal as it has a problem that the previous owner could not fix.
The interior is good but the bodywork needs a paint job.
The car drove fine for the first couple of days, then the transmission light came on and the car started bucking.
I turned it off and then back on again. After that it drove fine with no warning light.
The next day, the same problem. I put it in neutral, turned it off then back on. The light was out and the car drove fine.
Over the next couple of months it would sometimes go into that bucking mode.
One day the check engine light came on. I hooked a fault code reader. The following four codes were present :-
P1775 manfac trans control.
P0730 gear ratio incorrect.
P0139 O2 sensor.
P0122 pedal position sensor.
Any help would be much appreciated. Many thanks."

 

Tipptone, You are a true Gent!

 

Ok sorry for the last post im just trying to get some help or answers on fixing a problem so lets start again.........I bought a 1997 jaguar xjr supercharge v6 engine it looks to me as a straight 6 from a older gentleman that gave up on the car. He advised me when I purchased it that it needed looked at cause it gave some codes an had some problems it was a good deal an the car ran an drove fine at the time I was thinking he just cleared the codes with a (code)reader an told me what was wrong.as I tried to explain at first the car rode fine no problems at all passed inspection an everything a couple months passed I get into the car an begin to drive an the check engine light comes on then the transmission light came on an the car went into a "buck mode" where the car would jump when changing gears. So I pulled the car over turned it off then waited a few minutes then tried to start the car up again it fired right up the check engine was still on but the tranny light went off an the bucking mode stopped . When I got home I have a code reader so I hooked it up an the codes on the first comment I posted came up so I cleared the codes thinking it was something electrical. I then start driving it again with no problems for about a month then the same problems came back BUT also it was having a hard time when I tried to pull the car over an restart. It took a couple times an about 30 then the car started an I drove it home I havent drove it since. I was told it might be a throttle position sensor that might went bad that might not let it start and also I may need a ecu which I bought an changed but no help so I came on here to see if anyone else had this problem an steer me in the right direction im thinking its something electrical or a couple to a few problems not just one so please help me if you can thanks alot an any positive feedback is welcomed an appreciated.

 

Thank you I really appreciate that

 

Ok thanks

 

I agree thanks for your help

 

For your transmission codes, has the tranny ever been serviced? You might need a new filter and fresh fluid for the transmission. Some of the electrical solenoids may go bad, but they are cheap and easy to replace.

 

No since I bought the car I didnt change any transmission fluid or filter...electrical solenoids ill have to check also thanks again for any an all info if it helps I will definitely try

 

First, so you can be understood when discussing this problem, you apparently DO NOT have a V-6 engine. The term V-6 refers to 6 cylinders aligned in a V, not a straight line as you later describe. This stuff matters, Derek!

What I suspect is happening is a failure in the communications between the engine control module and the transmission control module. The connectors on the ecu and the TCU should be checked for corrosion. Although it is a long shot, you MOGHT be experiencing noise on that link from failing coils. Others have had unusual disturbances from that source.

Do you know where the ECU and TCU are located? If not, I suggest downloading the manuals and determining that.

 

First, some advice: Never just clear a code and hope it is some random electrical issue, especially if the code comes back. Codes don't usually trip a CEL/SEL light unless they have been set multiple times, and thus are usually valid. So simply clearing them will not solve the issue, as the codes are not the cause of the issue and instead are reporting what the ECU detects as what is usually a genuine fault.

Now among all the codes you report, the "P0122 pedal position sensor" code is what jumps out to me as an interesting clue.

While it is possible that you have several different failures interacting that would set transmission, pedal position sensor and O2 sensor codes, it is more likely that one of those is causing the others directly or indirectly. And it seems to me the most likely root cause could be related to that P0122 code as a faulty TPS could indeed cause transmission and fuel map issues.

Looking into that theory, what I'd suggest next is a forum search for "P0122" and see if others have faced this issue as well, if the symptoms are similar to yours and ultimately what the troubleshooting and resolution was.

So to help you out, I've done the search for you:

Jaguar Forums - Jaguar Enthusiasts Forum - Search Results


Now, next step I'd suggest is your taking a little time to read through the search results and see if that's a fit, generates some more specific questions or even sends you in another direction such as searching for the other codes and researching them.

I suspect from the the thread titles in the search results that you'll find some good information there.


Another side issue specific to the transmission to look into could be stress on the wiring harness that goes through the transmission tunnel under the console to the top of the 4L80E transmission. If your transmission mount is worn/loose, there is a known condition where this wiring harness is stretched & stressed and can cause some of the wires to break or come loose and cause various transmission issues. I don't really think this is your issue, but another to be aware of specific to the transmission. Fortunately the 4L80E used on the X300 XJR is very reliable, so I'd focus on engine issues versus transmission issues first. Although one should check that fluid is clean and filled as a simple check. A search on the wiring harness topic will also return several threads on that subject.


Good luck!

.

 

Just a note, on these cars IIRC when the engine stalls, bucks or hesitates it will sometimes throw a "transmission" light with the "X" through it. Gives the impression it's a trans problem when it's really not.